The present invention refers to a dental prosthesis for use with an oral implant of the type having an implant shaft inserted in a suitably prepared bore in a jawbone of a patient and an abutment which is connectable to the implant shaft and provided for support of a dental prosthesis or artificial tooth structure.
Dental implants of this type are known in the art. Conventionally, the prosthesis is cemented to the exposed support structure i.e. to the abutment. Cementing, however, is frequently insufficient to attain a secure attachment of the prosthesis. Therefore, it has been proposed to screw the prosthesis to the abutment, with the screw extending slightly slanted inside the prosthesis and being adapted for threaded engagement with the abutment. Such an attachment of the prosthesis to the abutment is sufficient when being able to place the implant shaft in proper alignment with the adjacent teeth. In some patients, however, bone disease may have been progressed to such an extent that available good bone is limited so that the dentist has to shift the placement of the implant shaft to the buccal side or lingual side. In these circumstances the predetermined fixed arrangement of the pin of the prosthesis with the abutment causes a problem when the implant shaft is not installed at an appropriate angle so that the edentulous area could not be restored without showing the prosthesis screw after engagement with the abutment.
In order to overcome this problem, U.S. Pat. No. 4,713,004 describes a dental implant with an implant shaft cooperating with an abutment which is adjustable by means of a ball and socket joint so as allow the dentist to position the abutment in a selected angled relationship with the implant shaft. Apart from using relatively complicated mechanical parts by employing such a ball and socket joint to alleviate the shifted alignment of implant shafts, the artificial dental prosthesis is still required to be cemented or screwed to the abutment.
A general problem of dental implants is the hygiene aspect because the patient is generally in no position to remove or detach the prosthesis properly once the prosthesis is cemented or screwed to the abutment so that the patient has to schedule a visit with the dentist. Moreover, also for the dentist the screwed or cemented attachment of the prosthesis to the abutment requires cumbersome work in order to remove and subsequently restore the dental implant.
A further problem encountered with conventional dental implants is the progressive loosening of the screwed connection between the abutment and the implant shaft.
U.S. Pat. No. 4,406,623 discloses a bone implant fixture for receiving a dental prosthesis, with the implant shaft being comparably of extended length in order to allow secure implantation of the implant fixture in the jawbone. Even though this publication is silent as to the manner of affixing the prosthesis to the abutment or section protruding above the bone, it can be assumed that the prosthesis is cemented or screwed thereto.